1. Field of the Invention
The present invention relates to inspection of network traffic to detect patterns in the traffic.
2. Description of the Related Technology
Today's Internet is rife with security threats that take the form of viruses and denial-of-service attacks, for example. Furthermore, there is much unwanted incoming information sent in the form of spam and undesired outgoing information containing corporate secrets. In large web server installations, there is the need to load balance traffic based on content of the individual communications. These trends, and others, drive demand for more sophisticated processing at various points in the network and at server front ends at wire speeds and near-wire speeds. These demands have given rise to anti-virus, intrusion detection and prevention, and content filtering technologies. At their core, these technologies depend on pattern matching. For example, anti-virus applications may look for fragments of executable code and Java and Visual Basic scripts that correspond uniquely to previously-captured viruses. Similarly, content filtering applications may look for a threshold number of words that match keywords on lists representative of the type of content (e.g., spam) to be identified. In like manner, enforcement of restricted access to web sites may be accomplished by checking the URL (Uniform Resource Locator) identified in the HTTP header against a forbidden list.